Sailing techniques often require the rapid shortening of foresail sheets and, in this operation, as a foresail sheet is shortened, the resistance to further shortening is increased to such an extent that even very strong people are not always able to sheet the foresail in as far as they would like, even with the most up-to-date hand-operated, geared sheet winches.
One way of alleviating this problem is to provide each sheet winch with an electric motor which can be driven from an electric storage battery carried by the yacht. However, this involves the use of relatively expensive and heavy storage batteries, particularly if the electric motors are designed to absorb the large amounts of power necessary to rapidly shorten the foresail sheets subject to relatively high tension. In addition, the drain on the electric storage batteries presents a serious safety hazard in that electric storage batteries in yachts are normally provided for the operation of electronic apparatus such as radio telephone and navigation equipment which are vital in an emergency. It is for this reason that the yachtsmen are reluctant to run the risk of overloading their electric storage batteries.